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Topic: Favourite chemistry experiment  (Read 33958 times)

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Offline mike

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Re:Favourite chemistry experiment
« Reply #15 on: November 01, 2005, 05:07:42 PM »
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My favourite experiment is the Marsh test (detection reaction for Arsenic)

Do you do this as an undergraduate experiment? Is it part of a specific toxicology course or is it done in general chemistry? It sounds interesting, I hadn't actually heard of it until now.

Can you do "real" samples? like hair, or soil?
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Offline Alberto_Kravina

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Re:Favourite chemistry experiment
« Reply #16 on: November 06, 2005, 08:03:38 AM »
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Can you do "real" samples? like hair, or soil?

Of course! I analyze only real samples (my specialliy are minerals). I have analyzed dozends of real samples...soil, minerals, wood, alloys (e.g. an aluminium can), samples of metal (e.g. metallic lead to determine the percentage of antimony), coal, ashes, washing powders and so on....It's really funny to analyze real samples... and I think it's quite boring to analyze a mixture of salts made by the teacher.

Quote
If I remember correctly, the presence of arsenic shows up as little dark spots in the solution, correct?

Not really...the nacent hydrogen produced by Zn and sulfuric acid reduces the arsenic compounds to arsine, and the arsine is heated => AsH3 --------HEAT--------> As + 1.5 H2
You identify the arsenic "mirror" (Very thin foil of elementar arsenic) because of it's black color. By the way....I once smelled the arsine gas, and the rotten garlic odor is pretty disgusing. I smelled ti only once because the mineral contained so much arsenic that a huge amount of arsine was created, so that the fume hood couldn't remove the whole gas, but fortunately nothing bad happened. (a more disgusting odor is the H2Se Odor (Rotting radishes))

Quote
Do you do this as an undergraduate experiment? Is it part of a specific toxicology course or is it done in general chemistry? It sounds interesting, I hadn't actually heard of it until now.

Not really, I have 8 hours of analytical laboratory per week in my school, and If I have to analyze a sample I make several tests for many different ions....one of this tests is the Marsh test.
« Last Edit: November 06, 2005, 08:17:14 AM by Alberto_Kravina »

Offline mike

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Favourite organic chemistry experiment
« Reply #17 on: April 04, 2006, 01:42:59 AM »
OK guys, I need your help with something. I need to get a bunch of ideas for some really neat organic chemistry experiments. Preferably organic synthetic reactions covering such things as nucleophilic substitution, elimination, formation of C-C single bonds etc at a second year level. I would also like to hear what peoples experiences are with stereochemistry labs, are there any that stand out in peoples minds.

I have also come up with a list of practical skills that an undergrad organic chemist may need to learn:

*recrystalisation
*melting points
*yield calculations
*Buchner filtration
*use of dropping funnel
*reflux
*distilation
*drying (with MgSO4 etc)
*bioling point measurements
*separatory funnel
*rotary evaporation
*IR
*extractions

And maybe some general skills:

*Synthetic experiment procedure (measure -> react -> quench -> work-up -> purify -> characterise)
*lab journal
*lab report write-up

What do you other chemist think?

Mike
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Offline Mitch

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Re:Favourite chemistry experiment
« Reply #18 on: April 04, 2006, 01:52:55 AM »
My favorite organic chemistry experiment was making Nylon. :)
I even kept my final product. Shhhh... :shhh:
« Last Edit: April 04, 2006, 01:53:18 AM by Mitch »
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Offline Yggdrasil

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Re:Favourite chemistry experiment
« Reply #19 on: April 04, 2006, 03:42:29 AM »
In my o-chem lab we performed a two-step, diastereoselective synthesis of 1,2-diphenyl-1,2-propanediol from benzaldehyde.  We first synthesized benzoin by coupling benzaldehyde to itself in the presence of thiamine and aqueous NaOH.  Afterward we reacted the benzoin with MeMgBr to synthesize 1,2-diphenyl-1,2-propanediol.  This step is diastereoselective beause of the Cram Chelate Rule (this was of particular interest becuase Cram was a professor at my school ;D).  Unfortunately, the experiment didn't work when our lab performed it because lab support gave us the regular diethyl ether instead of anhydrous diethyl ether for the second step, so the Grignard reagent died :'(.

Anyway, if you're interested here's a reference:
Ciaccio JA. et al. J. Chem. Educ. 2001, 78, 531.

Offline mir

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General skills
« Reply #20 on: April 04, 2006, 04:40:06 AM »
Quote
*Synthetic experiment procedure (measure -> react -> quench -> work-up -> purify -> characterise)

I am writing from my old labjournals now:

How about synthesising Chrysantemic acid?
It is a five step procedure, you can do it in three or four days on the lab. You start with a lot of materials, and end up with a few micrograms :-)

Or synthesising Sulphadrug? There is some historic value in it too.

Or DEET (Diethyl toluamide)? An insect repellent. You extract it as a oil.
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Offline tamim83

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Re:Favourite chemistry experiment
« Reply #21 on: April 04, 2006, 07:00:03 PM »
I have two favorite experiments as an undergrad.  In ochem lab I made a musk ketone as a "special project".  It was a multi-step synthesis in which I was just puting substituents on toluene until there were no hydrogens left on th ring.  I thought it was interesting to see the benzene ring peaks disappearing from my NMR each week.  It was very cool.  Also, we made alloys of copper and nickel in pchem lab next spring using cold boat fusion, or something like that at least.  Then we performed xray diffraction experiments on it.  That was awesome too.  I can't wait to teach labs next fall.   :)

Offline Borek

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Re:Favourite chemistry experiment
« Reply #22 on: April 05, 2006, 03:09:08 AM »
My favorite organic chemistry experiment was making Nylon. :)
I even kept my final product. Shhhh... :shhh:

About five years ago I still had mine too - but then I moved :(
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Offline P

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Re:Favourite chemistry experiment
« Reply #23 on: April 05, 2006, 07:54:55 AM »
Burning Mg was always cool (well, rather hot actually).     We were alowed to play with little bits to burn over the bunsen  -  the teacher used a gas jar full of oxygen to submerge the burning Mg in  -  obviosly alot brighter and more vigerous combustion.   Against the health and safety regulations, I managed to get her to let me have a go in front of the class - nice, but a bit scary at the time.  (we used to steal small strips of it to take home and burn...  Hmm).

Yes, as mentioned already - sodium etc. in water is brilliant!

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Offline Alberto_Kravina

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Re:Favourite chemistry experiment
« Reply #24 on: April 05, 2006, 03:14:43 PM »
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I even kept my final product. Shhhh... :shhh:
Hmmm...one of my nasty classmates stole some nitrocellulose about one year ago.
However, he put the stuff in his schoolbag where it underwent self-ignition....you can imagine what happened...
« Last Edit: April 05, 2006, 03:22:17 PM by Alberto_Kravina »

Offline constant thinker

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Re:General skills
« Reply #25 on: April 05, 2006, 04:41:49 PM »
Or DEET (Diethyl toluamide)? An insect repellent. You extract it as a oil.

Have you ever put a really high concentration of it on a bug. Yayyy, a good way to grow a third arm. ;)

Hmmm...one of my nasty classmates stole some nitrocellulose about one year ago.
However, he put the stuff in his schoolbag where it underwent self-ignition....you can imagine what happened...

Was your classmate wearing his bag when it self ignited..

My physical science teacher made nylon for me. I asked him how they mad it randomly one day, and after class he showed me.
« Last Edit: April 05, 2006, 04:45:31 PM by constant thinker »
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Offline mike

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Re:Favourite chemistry experiment
« Reply #26 on: April 06, 2006, 12:38:26 AM »
Ok so here is a modified list of the practical skills that a second year organic chemist should have:

use electronic balance (for solids and liquids)
pipettes
transferring solids and liquids
tare
magnetic stirrer (stirring / shaking)
hot plate (heating / cooling)
water bath
steam bath
dropping funnel
reflux (air & water condenser)
dry glassware
following the progress of a reaction
precipitate product
collect precipitate by filtration
washing crystals
crystallisation
Buchner filtration
recrystallisation
distillation
separatory funnel
drying with MgSO4 or CaCl2
rotary evaporator
sublimation
evaporation
liquid/liquid extraction
hot filtration
decolourising charcoal
chromatography
melting point
yield calculation
boiling point
infra red
refractive index
1H and 13C NMR
UV/vis
mass spec
Fumehood
MSDS
risk assessment
Lab journal
Report writing
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Offline Borek

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Re:Favourite chemistry experiment
« Reply #27 on: April 06, 2006, 02:09:50 AM »
Ok so here is a modified list of the practical skills that a second year organic chemist should have:

dropping funnel
Report writing

Are you sure funnel dropping is a usefull skill? I would rather go for funnel preserving :)
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Offline mike

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Re:Favourite chemistry experiment
« Reply #28 on: April 06, 2006, 05:50:19 AM »
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Are you sure funnel dropping is a usefull skill? I would rather go for funnel preserving  

haha :D yes good point. I think undergraduate students get quite good at dropping things. I used to love telling them how much things cost after they had broken them, poor students :D I am too mean.
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Offline Alberto_Kravina

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Re:Favourite chemistry experiment
« Reply #29 on: April 06, 2006, 07:36:44 AM »
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Was your classmate wearing his bag when it self ignited..
No! Actually, it self ignited during the Geography lesson :D ... he threw the burning bag (The bag was burning like hell! ) out of the window. Afterwards he jumped out of the window (we were having the lesson at the ground floor..) and put out the fire with snow.
Then he confessed that he stole the nitrocellulose and as a punishment he had to clean the stairs of our school for 40 days.... :o

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